Field of the Invention
The present invention relates to a method of controlling a clutch for vehicles in which inaccurate engine torque is compensated for and the clutch is controlled based on the compensated engine torque so as to improve control precision.
Description of Related Art
An automated manual transmission is a system in which a transmission based on a manual shift mechanism is automatically controlled, and such a transmission transmits engine torque using a dry clutch, differently from an automatic transmission using a torque converter and a wet multi-plate clutch.
However, the dry clutch has characteristics that clutch transmission torque is greatly changed according to various factors, such as tolerances of constituent elements abrasion degrees of the elements according to durability, thermal deformation of the elements due to high temperature, change in the coefficient of friction of a disc, etc., and thus it is difficult to estimate torque transmitted to the dry clutch during driving.
Therefore, if change of transmission torque is not recognized during control of the clutch, excessive slip of the clutch may occur or impact may be caused, and, thus, an algorithm to estimate torque characteristics of the dry clutch in real time is required.
Accordingly, transmission torque characteristics of a clutch were conventionally estimated through clutch control to estimate a torque-stroke curve (T-S curve), i.e., a transmission torque map characteristic curve of a dry clutch. Here, the T-S curve of the dry clutch is a curve in which transmission torque characteristics of the dry clutch according to strokes of a clutch actuator are collected to create a database.
Torque input to a transmission is engine torque, such engine torque is transmitted to wheels through a clutch. In order to secure stability in shift control, stability of engine torque input to the transmission is also important.
However, information regarding engine torque actually input from an engine may acquire accuracy only if drag torque modeling of the engine and load of an air conditioner, etc., should be accurately estimated, but such factors may not be accurately reflected in engine torque. Further, if an engine control unit (ECU) transmits incorrect engine torque information to a transmission control unit (TCU) under the condition that accuracy in engine torque is not secured, starting of a vehicle may be impossible or engine flare may occur at shift.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.